<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>04JS运算符</title>
</head>
<body>
<script>
    //除法会根据实际情况显示运算结果
    console.log(3/2);//1.5
    console.log(6/2);//3

    //如果比较运算符左右两边有数字,会转为数字再进行比较
    console.log(3>10);//false
    console.log(3>'10');//'10'会转为数字10,再进行比较,false
    console.log('3'>10);//false
    console.log("****************")
    //如果比较运算符左右两边都是字符串,会比较它们的编码值
    /* '3'.charCodeAt() 查看字符3的编码值 */
    console.log('3'>'10');//true 51>49
    console.log('超'>'博');
    console.log('3'.charCodeAt());//51
    console.log('10'.charCodeAt(0));//49
    console.log('1'.charCodeAt());//49


    //Number()将参数转为数字,如果得不到数值类型的结果,会得到NaN(Not a Number)
    console.log(Number('3'),typeof Number('3'));//3 'number'
    console.log(Number(true),typeof Number(true));//1 'number'
    console.log(Number(false),typeof Number(false));//0 'number'
    console.log(Number('你好'),typeof Number('你好'));//NaN 'number'

    let a = 1;
    let b = true;
    //松散比较运算符,只比较值,Number(true)=1
    console.log(a == b);//true
    //严格比较运算符,先比较类型,在比较值 number ≠ boolean
    console.log(a === b);//false

    //Boolean()将参数转为布尔类型的值
    //如果参数是0 空字符串 null undefined NaN 都会转为false
    console.log(Boolean(0));
    console.log(Boolean(''));
    console.log(Boolean(null));
    console.log(Boolean(undefined));
    console.log(Boolean(NaN));
    console.log(Boolean(' '));
    console.log(Boolean('下午好!'));

    //三元运算符
    let c = 0;
    console.log(c == 0 ? 'YES' : 'NO');//'YES'
    //=是赋值符号,给c赋值为0,Boolean(0)=false,所以取'NO'
    console.log(c = 0 ? 'YES' : 'NO');//'NO'
</script>
</body>
</html>